Biological information collecting probe, biological information measuring instrument, method for producing biological information collecting probe, and biological information measuring method

ABSTRACT

Provided are a biological information detecting probe and a biological information measuring apparatus that are easy to handle and can easily carry out highly accurate measurements by improving contact between a surface of a living body and a light sensor while minimizing damage to the body tissue, and a biological information measurement method for implementing the same. The invention also achieves a biological information measuring apparatus that can easily measure biological information concerning deep portions of a living body by improving contact between the surface of the living body and the light sensor, and a method for implementing the same. The biological information detecting probe comprises a raised portion  5  forming a recessed portion which is pressed against a living tissue in intimate contact relationship, a substrate  4,  an exit end face  9  from which detection light exits through one part of the recessed portion, and a light receiving means  11  which is provided in another part of the recessed portion and into which the detection light is introduced, wherein with the raised portion  5  and substrate  4  held pressed against the living tissue, the detection light is passed through the living tissue and introduced into the receiving means  11.

TECHNICAL FIELD

[0001] The present invention relates to a biological informationdetecting probe and a biological information measuring apparatus fornoninvasively measuring biological information, such as glucose, bloodsugar, water content, cholesterol, etc. in a living body, by measuringlight diffusely reflected from the living body or light passed through asuperficial tissue; the invention also relates to a fabrication methodfor such a biological information detecting probe, and a method ofmeasuring biological information.

BACKGROUND ART

[0002] In the prior art, various types of apparatus have been proposedfor noninvasively measuring the concentration of blood sugar in asubject.

[0003] In Japan Laid-Open Patent Publication No. 5-508336, for example,there is proposed a method for measuring the concentration of bloodsugar in a human subject by using near infrared radiation. According tothis method, the subject is irradiated with near infrared radiation atwavelengths of 600 nm to 1100 nm, and the blood sugar concentration isobtained by analyzing specific wavelength components of the light passedthrough the subject.

[0004] While near infrared light has the advantage that it is suitablefor analysis because, compared with infrared light, near infrared lightis less strongly absorbed by water and therefore easily passes throughaqueous solutions and living bodies, the disadvantages are that it isdifficult to extract information concerning individual componentsbecause the absorption peaks of various components overlap in acomplicated manner compared with infrared light, and that the absorptionpeak wavelength can easily change widely with temperature; with theseand other disadvantages, the near infrared method has not yet beenimplemented commercially.

[0005] As opposed to that, Japan Laid-Open Patent Publication No.11-178799 proposes a method for measuring glucose, water content, etc.in a superficial tissue of a living body by using near infraredradiation. According to this first prior art method, the superficialtissue of a living body, with a portion thereof raised, is placed in asingle groove formed in a flat member; in this condition, near infraredradiation is emitted from an optical fiber bundle placed on one side ofthe raised portion, and is received by an optical fiber bundle placed onthe opposite side of the raised portion. Then, a portion of the lightdiffusely reflected at the superficial tissue is detected and itsspectrum analyzed, to obtain biological information, in particular,glucose, water content, etc. of the dermis tissue.

[0006] As a prior art example using mid-infrared radiation, there isproposed, for example, in Japan Laid-Open Patent Publication No.9-11343, a method that uses an attenuated total reflection (hereinafterabbreviated ATR) measuring apparatus to measure specific constituents ofa subject, especially, a living body.

[0007] A schematic diagram illustrating this method is shown in FIG. 11.As shown, a transparent ATR prism 20 having a pair of reflectingsurfaces being parallel to each other on opposite sides thereof isplaced in intimate contact with a lip mucosa 21 to measure theconcentration of blood sugar. According to this method, the ATR prism isheld in a mouth between the upper and lower lips, and the light emergingfrom the ATR prism 20 after undergoing attenuated total reflection atthe interfaces between the lip mucosa 21 and the respective reflectingsurfaces of the prism 20 is analyzed.

[0008] In BME, vol. 5, No. 8 (Japanese Society of Medical Electronicsand Biological Engineering, 1991), there is proposed a method in which,after an ATR prism formed from a ZnSe optical crystal or the like isplaced in intimate contact with a lip mucosa, laser light at wavelengthsof 9 to 11 microns is introduced into the prism and caused to undergomultiple reflections within the prism, and the absorbed light isanalyzed to measure sugar blood and blood ethanol concentrations.According to this method, blood sugar and blood ethanol concentrationscan be measured noninvasively in real time.

[0009] These methods use an evanescent wave (so-called seeping light)for quantitative analysis. As shown in FIG. 11, the light travelingthrough the prism 20 is reflected after it slightly penetrates into thelip mucosa 21. As a result, the light penetrating into the lip isaffected by various constituents in the body fluid existing there.Therefore, by measuring the amount of reflected light, changes in thereflectance, absorptance, etc. of the body fluid can be detected, andeach component in the body fluid can thus be obtained.

[0010] There is also proposed Fourier transform Raman spectroscopy thatuses a laser light source such as an argon laser with an oscillationwavelength of 500 nm, a YAG laser with an oscillation wavelength of 1060nm, or a semiconductor laser with an oscillation wavelength of 880 nm,irradiates a living tissue with the laser light emitted from the lightsource, and obtains biological information by detecting the lightscattered within the living tissue (Raman scattered light) and byanalyzing the spectrum of the detected Raman scattered light. Accordingto this method, since the Raman scattered light has wavelengthscharacteristic of each individual kind of substance in the livingtissue, the kinds of substances in the living tissue and theirconcentrations can be calculated by analyzing the spectrum of the Ramanscattered light.

[0011] However, the prior art noninvasive blood sugar measuringapparatus described above have had the following problems.

[0012] The first prior art method has had the problem that if theoptical fiber at the incident side and the optical fiber at thereceiving side are not placed correctly opposite each other, the loss oflight within the living tissue increases and the intensity of diffuselyreflected light to be received decreases; furthermore, since the lightpenetrates deeply into the living tissue, there has been the problemthat various diffusely reflected lights differing in optical pathlength, containing information not only on epidermis and dermis but alsoon deeper portions of the living tissue such as subcutaneous tissue, aredetected.

[0013] Accordingly, when the target to be measured is skin tissue, ithas been difficult to extract and measure biological information only onthe superficial tissue of a livingbody, such as the epidermis about 100to 200 microns thick and the underlying dermis about 500 to 1000 micronsthick. In the case of mucous tissue also, it has been difficult tomeasure biological information only on the superficial tissue such asepitheliums and lamina propria mucosae.

[0014] Furthermore, when measuring components of light traveling instraight lines through a living tissue by using optical fibers placedopposite each other, a mechanical raising means is needed to verticallyraise the surface of the living tissue, which not only imposes an extrastrain on the living tissue but may cause a pain, and further, it hasbeen difficult to place the end face of each optical fiber in intimatecontact with the superficial tissue of the living body stably withconstant pressure.

[0015] Moreover, since very thin optical fibers need to be brought closeto the epidermic layer of the living body in order to precisely placethe optical fiber bundles in intimate contact with the living body, theapparatus is complex in construction and takes a cumbersome procedure toassemble, and besides, it has been difficult to form a large number ofgrooves.

[0016] Though a single groove formed in a flat member is placed inintimate contact with the living body in order to raise a portion of theliving body, it has been difficult to sufficiently raise the portion ofthe living body.

[0017] Furthermore, since it is difficult to increase the total area ofthe end face of the optical fibers, it has been difficult to increasethe intensity of diffusely reflected light used for measurement.

[0018] On the other hand, the second and third prior art methods havehad the following problems.

[0019] It is known that the depth, d, to which the evanescent wavepenetrates is roughly determined by the following equation (1).

[0020] [MATHEMATICAL 1] $\begin{matrix}{d = \frac{\lambda}{2\quad \pi \times \sqrt{{\sin^{2}\theta} - \left( \frac{n_{2}}{n_{1}} \right)^{2}}}} & (1)\end{matrix}$

[0021] Here, λ is the wavelength of light, θ is the angle of incidence,nl is the refractive index of the crystal, and n2 is the refractiveindex of the medium placed in contact with the crystal.

[0022] For example, when the wavelength of light is 10 microns, the ATRprism is formed from a ZnSe crystal (refractive index of about 2.41),the angle of incidence is 45 degrees, and the surrounding medium iswater (refractive index: about 1.0), then the penetration depth, d, canbe calculated as d=2.8 microns from the equation (1). If the refractiveindex of the surrounding medium changes, the seeping depth also changes,as can be seen from the equation (1), but in any case, the change is afew microns at most, which means that information concerning the surfaceof the living body and its neighborhood can be obtained using theabove-described prior ART measuring apparatus.

[0023] However, in this case, information concerning the portions of theliving body deeper than a few microns is difficult to obtain; inparticular, if there is an external disturbing layer such as an impurityor saliva between the apparatus and the analyte, the depth to which thesignal penetrates into the living body changes, causing the signal tochange.

[0024] Accordingly, in the above-described prior art methods whichrequire the ATR prism be pressed against a lip, the contact between thelip and the surface of the prism is not stable and it is difficult tomake measurements with high accuracy. Further, if saliva is presentbetween the prism and the lip, for example, the measured value will begreatly affected by the presence of the saliva.

[0025] The ATR prism used for the above purpose is formed from anoptical crystal such as ZnSe, ZnS, and KrS. Since these materials arevery soft and therefore require great care in handling and cleaning, itis difficult to measure many subjects in succession.

[0026] In the fourth prior art method, on the other hand, since thelaser light is directed into the living tissue, the laser light enteringthe living tissue is mostly absorbed in the living tissue. If Ramanscattered light of the intensity necessary to detect biologicalinformation is to be obtained, laser light of great intensity must beshone on the living tissue, but this has involved the problem that aburn may be caused because the laser light is absorbed in the livingtissue.

DISCLOSURE OF THE INVENTION

[0027] The present invention has been devised to solve theabove-enumerated problems, and an object of the invention is to providea biological information detecting probe that is easy to handle and caneasily measure a living tissue with high accuracy while minimizingdamage to the living tissue, and also provide a fabrication method forthe same, a biological information measuring apparatus, and a biologicalinformation measurement method.

[0028] To achieve the above object, a 1st invention of the presentinvention is a biological information detecting probe characterized bycomprising:

[0029] pressing means having a recessed portion which is pressed againsta living tissue;

[0030] detection light emitting means of emitting detection lightthrough one part of said recessed portion; and

[0031] detection light entrance means which is provided in another partof said recessed portion, and into which said detection light isintroduced, and in that:

[0032] said pressing means is formed from a material that has a higherrefractive index than said living tissue; and

[0033] with said pressing means held pressed against said living tissue,said detection light is introduced into said detection light entrancemeans after being passed through said living tissue fitted into saidrecessed portion.

[0034] A 2nd invention of the present invention is the biologicalinformation detecting probe as set forth in the 1st invention,characterized in that the angle formed by a plane containing said onepart of said recessed portion through which said detection light isemitted makes, and a plane containing said other part of said recessedportion through which said detection light enters is smaller than 180°.

[0035] A 3rd invention of the present invention is the biologicalinformation detecting probe as set forth in the 1st or 2nd invention,characterized by comprising:

[0036] a living tissue pressing part which is pressed against saidliving tissue and thereby deforms a portion of said living tissue; and

[0037] a base part which contacts a portion of said living tissue otherthan the portion thereof against which said living tissue pressing partis pressed, and in that:

[0038] said pressing means is formed extending over said living tissuepressing part and said base part.

[0039] A 4th invention of the present invention is the biologicalinformation detecting probe as set forth in the 3rd invention,characterized in that said living tissue pressing part and/or said basepart include secretion removing means of removing secretion releasedfrom said living tissue, said secretion removing means being located ina portion contacting said living tissue.

[0040] A 5th invention of the present invention is the biologicalinformation detecting probe as set forth in the 3rd or 4th invention,characterized in that

[0041] said detection light emitting means is provided in said livingtissue pressing part, and

[0042] said detection light entrance means is provided in said basepart.

[0043] A 6th invention of the present invention is the biologicalinformation detecting probe as set forth in the 3rd or 4th invention,characterized in that

[0044] said detection light emitting means is provided in said basepart, and

[0045] said detection light entrance means is provided in said livingtissue pressing part.

[0046] A 7th invention of the present invention is the biologicalinformation detecting probe as set forth in the 5th or 6th invention,characterized in that said detection light emitting means and/or saiddetection light entrance means include an optical waveguide.

[0047] An 8th invention of the present invention is the biologicalinformation detecting probe as set forth in the 7th invention,characterized in that said optical waveguide has a Y-branch shape or aplate-like shape.

[0048] A 9th invention of the present invention is the biologicalinformation detecting probe as set forth in the 7th or 8th invention,characterized in that

[0049] said optical waveguide in said detection light emitting means isfor receiving external input light, and

[0050] an end face of said optical waveguide, from which said detectionlight is not emitted, is formed so as to guide said input light to anend face from which said detection light is emitted.

[0051] A 10th invention of the present invention is the biologicalinformation detecting probe as set forth in the 9th invention,characterized in that said end face of said optical waveguide from whichsaid detection light is not emitted totally reflects said input lightfor input into said optical waveguide.

[0052] An 11th invention of the present invention is the biologicalinformation detecting probe as set forth in the 9th invention,characterized in that all or part of said end face of said opticalwaveguide from which said detection light is not emitted has a gratingstructure, and

[0053] said grating structure diffracts said input light for input intosaid optical waveguide.

[0054] A 12th invention of the present invention is the biologicalinformation detecting probe as set forth in the 7th invention,characterized in that said optical waveguide is formed from a materialselected from the group consisting at least of germanium, silicon, anddiamond.

[0055] A 13th invention of the present invention is the biologicalinformation detecting probe as set forth in the 7th invention,characterized in that said optical waveguide is surrounded with acladding material.

[0056] A 14th invention of the present invention is the biologicalinformation detecting probe as set forth in the 13th invention,characterized in that said optical waveguide is surrounded with acladding material that has a lower refractive index than said opticalwaveguide.

[0057] A 15th invention of the present invention is the biologicalinformation detecting probe as set forth in the 1st invention,characterized in that said base part is formed from a silicon material.

[0058] A 16th invention of the present invention is a fabrication methodfor the biological information detecting probe as set forth in any oneof the 1st to 15th inventions, including the step of forming saiddetection light emitting means and/or said detection light entrancemeans by depositing a germanium material.

[0059] An 18th invention of the present invention is the biologicalinformation detecting probe as set forth in the 1st invention,characterized in that said recessed portion is provided with a firstlight blocking film for blocking said detection light, said first lightblocking film being formed on a part of said recessed portion other thansaid one part and said other part thereof.

[0060] A 19th invention of the present invention is the biologicalinformation detecting probe as set forth in the 1st or 18th invention,characterized in that said recessed portion is substantially in theshape of an inverted triangle in a cross section taken parallel to alight path of said detection light, and a bottom of said recessedportion does not form a face.

[0061] A 20th invention of the present invention is the biologicalinformation detecting probe as set forth in the 1st or 18th invention,characterized in that said recessed portion is formed so as to have aface at its bottom.

[0062] A 21st invention of the present invention is the biologicalinformation detecting probe as set forth in the 20th invention,characterized in that the part on which said first light blocking filmis formed is the bottom of said recessed portion.

[0063] A 22nd invention of the present invention is the biologicalinformation detecting probe as set forth in the 1st or 18th invention,characterized in that a plurality of said recessed portions areprovided.

[0064] A 23rd invention of the present invention is the biologicalinformation detecting probe as set forth in the 22nd invention,characterized by comprising a second light blocking film formed betweensaid plurality of recessed portions.

[0065] A 24th invention of the present invention is the biologicalinformation detecting probe as set forth in the 22nd invention,characterized in that the light path of said detection light is one thatis projected from said detection light emitting means at an anglesmaller than the angle formed by a straight line joining the bottom ofsaid recessed portion to an edge of another recessed portion adjacent tosaid recessed portion, said edge being the part thereof nearest to saidbottom, and a straight line passing through said edges of said pluralityof recessed portions.

[0066] A 25th invention of the present invention is the biologicalinformation detecting probe as set forth in the 22nd invention,characterized in that said plurality of recessed portions comprise atleast two recessed portions having different depths.

[0067] A 26th invention of the present invention is the biologicalinformation detecting probe as set forth in any one of the 16th or 18thto 25th inventions, characterized in that said pressing means is formedfrom Si, Ge, SiC, or diamond.

[0068] A 27th invention of the present invention is a biologicalinformation measuring apparatus characterized by comprising:

[0069] the biological information detecting probe as set forth in anyone of the 1st to 15th inventions or the 18th to 25th invenitons;

[0070] a light source for said detection light; and

[0071] analyzing means of analyzing said detection light passed throughsaid living tissue and introduced into said biological informationdetecting probe, and in that:

[0072] said biological information measuring apparatus acquiresbiological information based on an analysis result obtained from saidanalyzing means.

[0073] A 28th invention of the present invention is a biologicalinformation measuring apparatus characterized by comprising:

[0074] the biological information detecting probe as set forth in anyone of the 1st to 15th inventions or the 18th to 25th inventions;

[0075] a light source for said detection light; and

[0076] analyzing means of analyzing scattered light generated when saiddetection light is introduced into said living tissue, and in that:

[0077] said biological information measuring apparatus acquiresbiological information based on an analysis result obtained from saidanalyzing means.

[0078] A 31st invention of the present invention is the biologicalinformation measuring apparatus as set forth in the 27th or 28thinvention, characterized in that said biological information detectingprobe depresses said living tissue to a depth not greater than 5 mm.

[0079] A 32nd invention of the present invention is the biologicalinformation measuring apparatus as set forth in the 27th or 28thinvention, characterized in that said biological information detectingprobe depresses said living tissue into a substantially curved shape.

[0080] A 33rd invention of the present invention is the biologicalinformation measuring apparatus as set forth in the 27th or 28thinvention, characterized in that the angle formed by a contact face thatcontacts and depresses said living tissue, and a line perpendicular to aplane containing said living tissue other than said contact face is notsmaller than 90°.

[0081] As described above, according to the present invention, aprojecting part is provided on the surface that is brought into contactwith a subject, and the living body is deformed by pressing theprojecting part against it; in this condition, light is shone on theliving body, and biological information is calculated by detecting thelight passed through the living body.

BRIEF DESCRIPTION OF THE DRAWINGS

[0082]FIG. 1 is a schematic drawing showing, in simplified form, abiological information measuring apparatus according to a firstembodiment of the present invention.

[0083]FIG. 2 is a diagram for explaining a light propagating path in abiological information measuring apparatus according to a secondembodiment of the present invention.

[0084]FIG. 3 is a schematic drawing showing the configuration of abiological information measuring apparatus according to one embodimentof the present invention.

[0085]FIG. 4 is a process diagram showing a fabrication method for abiological information detecting probe according to the same embodimentof the present invention.

[0086]FIG. 5 is a schematic drawing showing a biological informationdetecting probe and an input/output portion according to anotherembodiment of the present invention.

[0087]FIG. 6 is a process diagram showing a fabrication method for thebiological information detecting probe according to the same embodimentof the present invention.

[0088]FIG. 7 is a schematic drawing showing a biological informationdetecting probe according to a further embodiment of the presentinvention.

[0089]FIG. 8 is a schematic drawing showing configuration examples of abiological information detecting probe according to a further embodimentof the present invention.

[0090]FIG. 9 is a perspective view showing the shape of a raised portionof a biological information detecting probe according to one embodimentof the present invention.

[0091]FIG. 10 is a perspective view showing the shape of a raisedportion of a biological information detecting probe according to anotherembodiment of the present invention.

[0092]FIG. 11 is a schematic diagram showing one example of a prior artbiological information measuring apparatus.

DESCRIPTION OF THE REFERENCE NUMERALS

[0093]1. LIGHT SOURCE

[0094]2, 12. OPTICAL FIBER

[0095]3. LIGHT SENSOR

[0096]4. SUBSTRATE

[0097]5. RAISED PORTION

[0098]6, 16. HOLE

[0099]7. REFLECTING FACE

[0100]8. LIGHT EMITTING MEANS

[0101]9. EXIT END FACE

[0102]10. CLAD LAYER

[0103]11. LIGHT RECEIVING MEANS

[0104]13. LIGHT DETECTOR

[0105]14. SIGNAL PROCESSOR

[0106]15. DISPLAY DEVICE

[0107]20. ATR PRISM

[0108]21. LIP MUCOSA

[0109]31. BIOLOGICAL INFORMATION DETECTING PROBE

[0110]32, 310, 343. RECESSED PORTION

[0111]33, 311, 344. RAISED PORTION

[0112]34. LIGHT SOURCE

[0113]35. LIGHT DETECTOR

[0114]36. SIGNAL PROCESSOR

[0115]37. DISPLAY DEVICE

[0116]38. LIVING TISSUE

[0117]39. INPUT/OUTPUT PORTION

[0118]320, 340. SILICON SUBSTRATE

[0119]321, 322, 341, 342. OXIDE

Best Mode for Carrying Out the Invention

[0120] Embodiments of the present invention will be described in detailbelow with reference to drawings.

[0121] A biological information measuring apparatus according to anembodiment of the present invention comprises a light source, asubstrate having a raised portion for depressing a surface of a livingbody, a light emitting means which is provided on the substrate andwhich emits light produced by the light source onto the surface of theliving body, a light receiving means which receives the light emittedfrom the light emitting means, a detector for detecting the lightreceived by the light receiving means, and a signal processor forcalculating biological information using a signal obtained by thedetector, wherein either the light emitting means or the light receivingmeans is disposed in the raised portion formed on the substrate.

[0122] In a preferred mode of the biological information measuringapparatus according to the embodiment of the present invention, thelight emitting means and the light receiving means are formed fromgermanium.

[0123] (Embodiment 1)

[0124] A biological information measuring apparatus according to a firstembodiment of the present invention will be described below withreference to FIG. 1. In the figure, reference numeral 1 is a lightsource, 2 and 12 are optical fibers, 3 is a light sensor, 4 is asubstrate, 5 is a raised portion, 6 and 16 are holes, 7 is a reflectingface, 8 is a light emitting means, 9 is an exit end face, 10 is a cladlayer, 11 is a light receiving means, 13 is a light detector, 14 is asignal processor, and 15 is a display device.

[0125] A high intensity ceramic light source that emits light atwavelengths of 1.3 to 10 microns, for example, is used as the lightsource 1. A CO₂ laser may be used instead. The optical fiber 2 transmitsthe light emitted from the light source 1 and guides it to the lightsensor 3. An infrared optical fiber formed from silver bromide or silverchloride based material, a chalcogenide optical fiber, or an opticalfiber of hollow structure is used as the optical fiber here.

[0126] The light sensor 3 is placed in intimate contact with the surfaceof a living body, such as a lip mucosa 21, as shown in the figure, forexample, and the raised portion 5 formed on the substrate 4 of the lightsensor 3 acts to depress the surface of the living body. The amount ofdepression is preferably 5 mm or less, but is not specifically limitedas long as the light sensor can be brought into intimate contact withthe living tissue.

[0127] The substrate 4 is formed, for example, from a fluoro resin,reinforced plastic, silicon, or glass.

[0128] Forming the raised portion 5 in a curved shape as shown is highlydesirable from the standpoint of alleviating the pain inflicted on theliving body as well as enhancing the adhesion to it.

[0129] The optical fiber 2 is inserted in the hole 6 formed through thesubstrate 4, and the light guided through the optical fiber 2 isintroduced into the raised portion 5.

[0130] The reflecting face 7 of the raised portion 5 is not specificallylimited in shape, but preferably it is shaped so as to provide an angleat which the light reaching it is totally reflected.

[0131] Though not shown here, it is also preferable to provide a gratingso that the light from the light source is introduced into the lightemitting means 8.

[0132] Also preferably, the light emitting means 8 is surrounded withthe clad layer 10 which protects the light emitting means 8 and alsoacts as an optical buffer layer to prevent seeping light from the lightemitting means 8 from being attenuated by contacting a highly absorbentSubstance.

[0133] The material for the light emitting means 8 should be transparentto radiation in the wavelength region used; for example, germanium,silicon, diamond, and silver bromide or silver chloride based materialsare preferred for use. Silicon not doped with impurities such asphosphorus or boron is further preferred because transparency at theinfrared band is then enhanced. The light emitting means 8 is shown inthe figure as being formed in a plate-like shape, but it may be formedin a Y-branch shape.

[0134] A material relatively transparent at the light wavelengths in theinfrared region and having a refractive index smaller than that of thelight emitting means 8 is used for the clad layer 10. For example, afluoro resin is a preferred material; when the light emitting means 8 isformed from germanium, silicon is also preferred.

[0135] Preferably, the substrate 4 is constructed, for example, from asilicon or glass substrate or a substrate made of heat resistant resin,and silicon as the clad layer and germanium as the light emitting meansare deposited on the substrate 4 by using a film deposition process suchas sputtering or electron beam deposition.

[0136] It is preferable that the exit end face 9 of the light emittingmeans 8 be not formed vertical, because it would then impair adhesion tothe living tissue, but be formed somewhat slanted as shown in thepresent embodiment.

[0137] The operation of the biological information measuring apparatusof the present embodiment having the above configuration will bedescribed below.

[0138] The light emitted from the light source 1 and introduced throughthe optical fiber 2 and the clad layer 10 into the raised portion 5 isreflected by the reflecting face 7 formed on the side face of the raisedportion 5, and is input into the light emitting means 8.

[0139] The light input into the light emitting means 8 is guidedtherethrough and emitted through the exit end face 9 into the livingtissue 17.

[0140] Next, the propagation path of the light emitted through the exitend face 9 will be briefly described below.

[0141] Referring to FIG. 2, an explanation will be given of how thelight propagating in straight lines through the center of the lightemitting means 8 travels when the angle of the exit end face 9 is 15degrees relative to the normal to the substrate 4.

[0142] The following explanation is given by taking as an example thecase where the light emitting means 8 is formed from germanium with arefractive index n₁=4.0, and the refractive index n₂ of the livingtissue 17 is 1.5.

[0143] Assuming that the light propagating in straight lines through thecenter of the light emitting means 8 is incident at an incidence angle θin on the exit end face 9, the incident light emerges at an emergenceangle θ out to enter the living tissue 17 in accordance with Snell'sequation given below.

[0144] [MATHEMATICAL 2]

n ₁×sin(θ in)=n ₂×sin(θ out)

[0145] Substituting the above values in this equation, the emergenceangle θ out is calculated as 43.6 degrees; therefore, the light emittedfrom the light emitting means 8 is refracted toward the bottom in thefigure as it enters the living tissue 17. The light entering the livingtissue 17 travels therethrough while being partially scattered, andreaches the light receiving means 11.

[0146] Assuming that the angle that the longitudinal direction of thelight emitting means 8 makes with the longitudinal direction of thelight receiving means 11 is 90 degrees, the light passed through theliving tissue 17 is incident at an incidence angle (90 degrees−(θ out−θin)) on the light receiving means 11. Substituting the above values, theconcrete incidence angle is calculated as 61.4 degrees. The light isrefracted as it enters the light receiving means 11. If the lightreceiving means 11 is also formed from germanium, the light enters at anangle of 19.2 degrees according to Snell's equation given above, andpropagates through the light receiving means 11.

[0147] In this way, in the present embodiment, since germanium having arelatively high refractive index is used for the light emitting means 8,the refraction angle when the light enters the living tissue 17 is verylarge; as a result, there is no need to position the light receivingmeans 11 directly opposite the light emitting means 8, and the light canbe received by the light receiving means 11 whose position is differentby 90 degrees axis to that of the light receiving means 11, as shown inFIG. 1. This feature is extremely useful because, by just depressing thesurface of the living body into an extremely gently curved shape, theliving tissue can be measured while maintaining good adhesion to it andwithout hurting the living body.

[0148] The above description has been given by dealing with the lighttraveling in straight lines through the light emitting means 8, but someof the light travels in zigzag lines through the light emitting means 6.The above principle also holds for the case of such zigzagging light,and the part of the light emitted through the exit end face 9 can bemade to reach the light receiving means 8.

[0149] Next, the operation of the present embodiment will be described.The light entering the light receiving means 11 is transmitted throughthe optical fiber 12 and reaches the light detector 13 which performsvarious kinds of spectrum analyses including conversion into anelectrical signal for each wavelength component.

[0150] When the concentration of an absorbing substance in the livingtissue 17 changes, signal strength at a particular wavelength alsochanges; therefore, by measuring the signal strength, biologicalinformation such as the concentration of glucose can be calculated inthe signal processor 14. The biological information thus calculated isdisplayed on the display device 15.

[0151] The hole 16 formed through the substrate 4 serves to removeimpurities such as saliva present between the living tissue and thebiological sensor 3. This enhances the adhesion between the livingtissue and the light sensor, and allows highly accurate measurements ofbiological information by preventing the attenuation of light andchanges in characteristics that can occur when the light is transmittedthrough impurities.

[0152] Thus, the biological information measuring apparatus according tothe present embodiment offers a great advantage because, when theinvention is applied, not only can biological information be measuredwhile maintaining good contact between the light sensor and the surfaceof the living body, but the distance between the light exit end face 9and the light incident face of the light receiving means 11 can be setat any suitable value according to the design requirement.

[0153] This serves to greatly improve the seeping depth of a few micronsof the seeping light called the evanescent wave, which, in the prior artATR method, is determined by the refractive index of the prism materialand the refractive index at the surface of the living body; this notonly makes it easy to measure the portions of the living body deeperthan a few microns, but the path length of the light propagating throughthe living body can also be increased easily, so that the opticalcharacteristics of any particular component in the living body even ifit is very minute, can be also measured easily.

[0154] It is preferable to make the light sensor 3 detachable from thelight source 1 and light detector 13 or from the optical fibers 2 and12, since it can then be easily replaced when the surface of the lightsensor is soiled or scratched after measuring biological information.

[0155] The biological information measuring probe of the presentinvention corresponds to the structure comprising the substrate 4,raised portion 5, light emitting means 8, clad layer 10, and lightentrance means 11 in the present embodiment, and the secretion removingmeans of the present invention corresponds to the hole 16 in the presentembodiment. The living tissue pressing part of the present inventioncorresponds to the raised portion 5 in the present embodiment, and thebase part of the present invention corresponds to the substrate 4 in thepresent embodiment, which, together with the exit end face 9 and thelight receiving means 11, constitute the pressing means of the presentinvention. The optical waveguide in the detection light emitting meansof the present invention corresponds to the light emitting means 8 inthe present embodiment, and the detection light entrance means of thepresent invention corresponds to the light entrance means 11 in thepresent embodiment. The light source of the present inventioncorresponds to the light source 1 and optical fiber 2 in the firstembodiment, and the analyzing means of the present invention correspondsto the structure comprising the optical fiber 12 light detector 13,signal processor 14, and display device 15 in the present embodiment.

[0156] The above embodiment has been described assuming that the livingtissue 17 is placed in intimate contact with the clad layer 10 and thesubstrate 4, but the pressing means of the present invention is notlimited to this particular structure; for example, the structure may besuch that the living tissue is fitted in a recessed portion, the onlyrequirement being that the living tissue be placed in contact with onepart of the recessed portion through which detection light exits andwith another part thereof into which the emitted detection light isintroduced. For example, in the present embodiment, if the living tissue17 is placed in contact with at least the exit end face 9 and the lightreceiving means 11, the same effect as described above can be obtainedeven if other portions of the living tissue 17 are not in contact withthe substrate 4 or the recessed portion 5 in the vicinity of the hole16.

[0157] (Embodiment 2)

[0158] A second embodiment of the present invention will be describedbelow with reference to FIG. 3. FIG. 3 is a schematic diagram showing abiological information measuring apparatus according to the secondembodiment of the present invention.

[0159] A biological information detecting probe 31 is constructed using,for example, a silicon single-crystal substrate transparent atwavelengths of 1.1 to 10 microns. A material whose content of impuritiessuch as boron and phosphorus is low, and whose resistivity is notsmaller than 100 Ωcm, is particularly preferable. A material withresistivity not smaller than 1500 Ωcm is more preferable. Such highresistivity silicon has high transmittance at infrared wavelengths ofabout 9 to 10 microns, and is preferred when measuring glucose or othersubstances that have absorption regions in this wavelength band.

[0160] A plurality of recessed portions 32 and raised portions 33, eachformed in a trapezoidal shape having the same depth h, are formed inperiodically repeating fashion on the surface of the biologicalinformation detecting probe 31. These recessed portions 32 and raisedportions 33 serve to deform the living tissue 38 when the biologicalinformation detecting probe 31 is pressed against the living tissue 38.

[0161] The depth h of the recessed portions 32 is not specificallylimited, but when it is set to about 100 microns, biological informationmainly concerning the epidermis can be measured because the raisedportions 33 are pressed only into the epidermis of the living tissue 38.When it is set to about 200 microns, on the other hand, biologicalinformation concerning the dermis as well as the epidermis can bedetected. In this way, by adjusting the depth h of the recessed portions32, the depth in the living tissue 38 at which the measurement is to betaken can be easily controlled. In the present embodiment, h is set to100 microns.

[0162] The top width W₁ of the raised portions 33 is not specificallylimited, but if the width is too large, it becomes difficult to pressthe raised portions 33 into the living tissue 38; therefore, it ispreferable to set the width to 1 mm or less. In the present embodiment,W₁ is set to 100 microns.

[0163] The bottom width W₂ of the recessed portions 32 is notspecifically limited, but if the width is too small compared with W₁, itbecomes difficult to press the raised portions 33 into the living tissue38; therefore, it is preferable that W₂ be set not smaller than W₁. W₂is a parameter that determines the path length of the light propagatingthrough the living tissue 38, and when making measurements in theinfrared wavelength region where absorption by water is particularlylarge, if W₂ is too large, light is absorbed and the transmittance dropssignificantly. For example, at wavelengths longer than about 39 microns,light is substantially absorbed by water; therefore, it is preferablethat W₂ be set to 300 microns or less. More preferably, W₂ should be setto 200 microns or less. In the present embodiment, W₂ is set to 100microns.

[0164] The side slope angle θ₁ of the recessed portions 32 is notspecifically limited, but if it is close to 90 degrees, it becomesdifficult to press them into contact with the living tissue 38;therefore, it is preferable that the angle be set smaller. In thepresent embodiment, θ₁ is set to 54.7 degrees.

[0165] The portion 310 where detection light enters the biologicalinformation detecting probe 31 and the portion 311 where the detectionlight exits the biological information detecting probe 31 are eachformed slantingly relative to the surface of the biological informationdetecting probe 31, as shown in FIG. 3, so that the light can enter andexit without undergoing total reflection in the biological informationdetecting probe 31. In the and thus, the light can be made to enter andexit the biological information detecting probe 31 efficiently. In thepresent embodiment, the slope angle θ₂ of each of the detection lightentrance portion 310 and exit portion 311 is set to 111.6 degrees.

[0166] A fabrication method for the biological information detectingprobe 31 according to the present embodiment will be described belowwith reference to FIG. 4.

[0167] Anisotropic wet etching was used for the fabrication of thebiological information detecting probe 31 made of single-crystalsilicon. This method is chemical etching that uses an aqueous solutionof KOH or an aqueous solution of ethylenediamine, and utilizes theproperty that the etching rate along the (111) direction ofsingle-crystal silicon is extremely low compared with that along anyother direction.

[0168] First, as shown in FIG. 4(a), oxide films 321 and 322 are formedas protective layers on the upper and lower surfaces of thesingle-crystal silicon substrate 320.

[0169] Next, the oxide film 321 is patterned in the desired shape, asshown in FIG. 4(b).

[0170] After that, the silicon substrate 320 is immersed, for example,in a 40% solution of KOH for etching. When the silicon wafer whose (100)crystal plane is oriented along the direction of the normal to thesurface is etched, recessed portions 32 whose side faces are slanted atan angle of 54.7 degrees are formed as shown in FIG. 4(c) After formingthe recessed portions 32, the oxide film 321 is removed, resulting inthe formation of raised portions 33 between the recessed portions 32, asshown in FIG. 4(d). Here, the protective layers may be formed usingsilicon nitride films.

[0171] The above has described the method that forms the recessedportions 32 by anisotropic wet etching of the silicon single-crystalsubstrate, but instead, ultrasonic machining may be used.

[0172] Ultrasonic machining is a machining method that grinds materialby abrasive grit; in this method, while applying vibrations of afrequency of 20 kilohertz and an amplitude of 30 microns or larger to atool having the shape corresponding to the finished shape, abrasive gritsuch as boron carbide is supplied in a slurry and the tool is pressedagainst the workpiece to be machined.

[0173] The entrance portion 310 and exit portion 311 on the back of thebiological information detecting probe 31 of the present invention canalso be formed using the same method as described above.

[0174] Next, the principle of operation of the biological informationmeasuring apparatus of the present invention will be described belowwith reference to FIG. 3.

[0175] Part of the light emitted from the light source 34 and introducedinto the biological information detecting probe 31 through the incidentportion 310 reaches a side face of a recessed portion 32. The incidenceangle of the detection light on the slanted face of the recessed portion32 is set so that, of the light entering the living tissue 38,rectilinearly propagating components again reach the recessed portion32, by considering the refractive index of the living tissue 38, therefractive index of the biological information detecting probe 31, andthe angle of the side face of the recessed portion 32. Preferably, theincidence angle is set so that when the living tissue 38 is placed incontact with the recessed portion 32, the light travels through theliving tissue 38 horizontally in the figure.

[0176] For example, when the side face of the recessed portion 32 isslanted at an angle of 54.7 degrees, and when the refractive index ofthe living tissue 38 is n₂=1.4 and that of the silicon forming thebiological information detecting probe 31 is n₁=3.418, the light is toincident on the slanted face of the recessed portion 32 at an angleθ₃=13.7 degrees. Since the biological information detecting probe 31 ofthe present embodiment is constructed using silicon which is a substanceof high refractive index, the difference from the refractive index ofthe living tissue 38 is large; as a result, by tilting the incidentlight by the small angle θ₃ relative to the slanted face of the recessedportion 32, the detection light can be refracted at a large angle, andthus the refraction angle θ₄ at which the light enters the living tissue38 can be made large.

[0177] The refraction angle θ₄ can be calculated by Snell's equation(equation 3) given below.

[0178] [MATHEMATICAL 3]

n ₁×sin θ₃ =n ₂×sin θ₄

[0179] From equation 3, θ₄=35.3 degrees. Refracting the light by θ₄=35.3degrees relative to the slanted face of the recessed portion 32 meansthat the light is deflected into a substantially horizontal direction inFIG. 3.

[0180] It is generally known that light propagating through a livingbody is scattered and diffused, but when the method of the invention isused, rectilinearly propagating light having the highest intensity canbe received at the side face of the other raised portion located on theopposite side.

[0181] The detection light passed through the living tissue 38 entersthe biological information detecting probe 1 by being refracted at theface where it exits the living tissue 38, just as it was refracted whenentering the living tissue 38. After that, the detection light isemitted outside the biological information detecting probe 31 anddetected by the light detector 35. Based on the detection result fromthe light detector 35, biological information is calculated in thesignal processor 36, and the result is displayed on the display device37.

[0182] The light detected by the light detector 35 contains many lightcomponents passed through the interior of the living tissue 38,especially, the superficial tissue, but less components carryingbiological information from deeper portions of the living body such assubcutaneous fatty tissue; therefore, by analyzing the spectrum of thedetected light, biological information concerning the target layer inthe living tissue can be measured easily and with high sensitivity.

[0183] There are cases where good contact cannot be obtained between therecessed portion 32 of the biological information detecting probe 31 andthe living tissue 38 at the lower end of the side face of the recessedportion 32.

[0184] However, in many of such cases, air exists in the gap createdbetween the living tissue 38 and the side face of the recessed portion32. Since the refractive index of air is n=1.0, the difference from therefractive index of the biological information detecting probe 31 isgreater than the difference from that of the living tissue, which meansthat, in this air gap, the light is refracted at a larger angle than thelight passing through the contacted living tissue 38, and therefore, isdirected away from the normal light path.

[0185] As a result, unwanted light that does not contain biologicalinformation exits the biological information detecting probe 31 at adifferent angle, and such light is therefore not detected by the lightdetector 35, that is, unwanted light is eliminated, and biologicalinformation can thus be calculated correctly.

[0186] (Embodiment 3)

[0187] A third embodiment of the present invention will be describedbelow with reference to FIG. 5. FIG. 5 is a schematic diagram showing abiological information detecting probe according to the secondembodiment of the present invention.

[0188] The biological information detecting probe 31 is constructedusing a silicon single-crystal substrate, the same material as that usedin the second embodiment. A plurality of recessed portions 32 and raisedportions 33, each formed in a triangular shape having the same depth h,are formed in periodically repeating fashion on the surface of thebiological information detecting probe 31. These recessed portions 32and raised portions 33 serve to deform the living tissue 38 when thebiological information detecting probe 31 is pressed against the livingtissue 38. In the present embodiment, h=100 microns. The side slopeangle θ₁ of the recessed portions 32 is set to 31.5 degrees.

[0189] An input/output portion 39 made of Ge is formed on the back ofthe biological information detecting probe 31. The portion wheredetection light enters the input/output portion 39 and the portion wherethe detection light exits the input/output portion 39 are each formedslantingly relative to the interface between the biological informationdetecting probe 31 and the input/output portion 39, as shown in FIG. 5,so that the light can enter and exit without undergoing total reflectionin the input/output section 39. In the present embodiment, the slopeangle θ₂ of each of the detection light entrance portion 310 and exitportion 311 is set to 138.6 degrees.

[0190] A fabrication method for the biological information detectingprobe 31 according to the present embodiment will be described belowwith reference to FIGS. 6(a) to 6(d).

[0191] As in the second embodiment, after forming oxide films 341 and342 on the upper and lower surfaces of the silicon single-crystalsubstrate 340, a desired pattern is formed as shown in FIG. 6(a).

[0192] Next, the silicon substrate 340 is immersed, for example, in a40% solution of KOH for etching. When the silicon wafer whose (100)crystal plane is oriented along the direction of the normal to thesurface is etched, raised portions 344 and recessed portions 343 (Vgrooves) whose side faces are slanted at an angle of 54.7 degrees areformed as shown in FIG. 6(b). When etching is continued after the Vgrooves are formed, the (111) crystal plane is gradually etched, and theV grooves widen and grow, as shown in FIG. 6(c).

[0193] When etching is further continued, the oxide film 341 remainingon the vertex of each raised portion 344 is removed, and the (100)crystal plane at the vertex is etched. Since the (100) crystal plane isetched at a faster rate than the (111) crystal plane, the vertex isetched and the height decreases gradually as the time elapses, and whenthe etching is stopped at a particular point in time, for example, Vgrooves formed by the (311) crystal plane result, as shown in FIG. 6(d).

[0194] The back surface of the biological information detecting probe ofthe present invention can also be processed using the same method asused in the second or third embodiment.

[0195] The bonding between the biological information detecting probe 31and the input/output portion 39 can be accomplished, for example, bypolishing the contact faces smooth and joining them together usinginteratomic forces acting between them.

[0196] Alternatively, pressure may be applied by holding them in contactwith each other. Any suitable method may be used as long as the lightcan be propagated from the input/output portion 39 to the biologicalinformation detecting probe 31 and vice versa without causing totalreflection at the interface.

[0197] When the biological information detecting probe 31 of the presentembodiment is used in a biological information measuring apparatussimilar to the one of the second embodiment, biological informationconcerning the target layer in the living tissue can be measured easilyand with high sensitivity, as in the second embodiment.

[0198] The biological information detecting probe 31 of the presentembodiment provides a large contact angle of 117 degrees and thusensures very smooth contact with the living tissue 38. Therefore, whenthe biological information detecting probe 31 is pressed against theliving tissue 38, not only can the raised portions 33 of the biologicalinformation detecting probe 31 be easily pressed into the living tissue38, but the living tissue 38 can also be easily made to contact the sidefaces of the recessed portions 32 firmly. Furthermore, since the area ofthe contact surface with the living tissue 38 is increased, much of thedetection light can be introduced into the living tissue 38, eliminatingthe need to collect light using expensive lenses.

[0199] (Embodiment 4)

[0200] A fourth embodiment of the present invention will be describedwith reference to FIG. 7. FIG. 7 is a schematic diagram showing abiological information detecting probe according to the fourthembodiment of the present invention.

[0201] As in the second embodiment, a single-crystal silicon substrateis anisotropically etched to form recessed portions 32 with side facesslanted at an angle of 54.7 degrees, but the difference from the secondembodiment is that a periodic pattern of recessed portions 310 andraised portions 311 is also formed on the back surface of thesingle-crystal silicon substrate, in which the side faces of therecessed portions 310 and raised portions 311 serve as the detectionlight entrance portion 310 and reflecting portion 311.

[0202] The side slope angle of each recessed portion 310 should be setat such an angle that does not cause total reflection of the detectionlight, and an angle of about 80 degrees is preferable; such recessedportions can be easily formed using an ultrasonic-machining method.

[0203] Light reaching the side face of a raised portion 310 on the backsurface of the biological information detecting probe 31 propagates in astraight line through the inside of the biological information detectingprobe 31, and reaches the side face of a recessed portion 32 formed onthe side of the probe that contacts the living body. After that, thelight is refracted at a large angle because of the difference inrefractive index between the living tissue and the biologicalinformation detecting probe, passes through the superficial tissue ofthe living body, and again reaches the side face of the recessed portion32, at which the light is refracted in the direction of the raisedportion 311 formed on the back surface. Since at the position therefracted light reaches, the side face of the raised portion 311 is set,the light is passed therethrough without total reflection and is emittedoutside. When compared with the configuration example shown in FIG. 8(b)to be described later, the above-described structure can reduce thethickness, size, and weight of the biological information detectingprobe 31 in a configuration where a plurality of light sources areprovided.

[0204] When the biological information detecting probe 31 of the presentembodiment is used in a biological information measuring apparatussimilar to the one of the second embodiment, biological informationconcerning the target layer in the living tissue can be measured easilyand with high sensitivity, as in the second embodiment.

[0205] The above embodiment has been described by dealing with the casewhere the detection light entering the biological information detectingprobe after passing through the living tissue is analyzed, butalternatively, biological information may be obtained by using laserlight, such as that generated by an argon laser, a YAG laser, or asemiconductor laser, as detection light, and by analyzing the scatteredlight generated when the detection light propagates through the livingtissue. When the biological information detecting probe of the presentinvention is used, much of the detection light introduced into theliving tissue can be fed back to the biological information detectingprobe; as a result, even when high intensity laser light is used, damageto the living tissue can be reduced, and the problem of burning causedby the projection of the detection light can be eliminated.

[0206] Next, FIGS. 8(a) to 8(c) show other configuration examples of thebiological information detecting probe according to the second to fourthembodiments. FIG. 8(a) shows an example in which the recessed portions32 are each formed in the shape of a V groove in a cross section takenparallel to the light path of the detection light. As shown, the crosssection of each recessed portion 32 consists only of side faces 32 a and32 b, and has a pointed bottom 32 c which does not have a widthcorresponding to the wide W₂ in the above embodiment.

[0207] In this example, all of the detection light from the light sourceenters through the side faces 32 a of the recessed portions 32, ispassed through the living tissue 18, and exits from the side faces 32 b.

[0208] According to this configuration example, since there are nounwanted light components in the light emitted from the light source 4,a wide light source 34 a that can produce wider light than the lightsource of the above embodiment can be used more efficiently as detectionlight.

[0209] In order for all of the detection light to enter through the sidefaces 32 a, the incidence angle of the incident light should be madesmaller than the angle formed by a straight line joining the bottom 32 cto an edge 32 d of a recessed portion 32 located adjacent to therecessed portion 32 having that bottom 32 c, and a straight line joininga plurality of edges 32 d. With this setting, the detection lightemitted from the light source can be prevented from entering the livingtissue 38 through the raised portions 33, not through the recessedportions 32.

[0210]FIG. 8(b) shows a configuration example in which a plurality oflight sources 34 are provided. In this configuration, since detectionlight emitted from each individual light source can be detectedindependently of the others, more accurate values can be obtained basedon the detection results of individual detection light.

[0211]FIG. 8(c) shows an example in which a light blocking film 312 isformed on the bottom 32 e of each recessed portion 32 and a lightblocking film 313 on the top of each raised portion 32. The lightblocking film 313 serves to prevent the detection light from passingthrough the top of the raised portion 33 and entering the living tissue32, and also prevent light reflected from the light blocking film 313from exiting from the exit face 311. On the other hand, the lightblocking film 312 serves to prevent the detection light from enteringthrough the bottom 32 e, and also prevent light from being reflected atthe bottom 32 e and exiting from the exit face 311.

[0212]FIG. 8(d) shows an alternative configuration example of the fourthembodiment, in which light blocking films 314 are formed on the bottomsof the recessed portions 310 and raised portions 311 formed inperiodically repeating fashion on the back surface of the siliconsingle-crystal substrate. With this configuration, a light source thatcan produce wide laser light, such as the wide light source 34 a shownin the configuration example of FIG. 8(a), can be used to generatedetection light.

[0213] In the above description, it is desirable that the light blockingfilms 312 to 314 be each provided with a light absorbing orantireflection function.

[0214] The biological information detecting probe of each of the aboveembodiments can be used by placing it in direct contact with a finger,lip, arm, earlobe, or other part of a living body, but when measuringbiological information by placing the biological information detectingprobe in contact with a lip, saliva may be trapped between them. It istherefore preferable that a hole, a deep groove, or like means forremoving the saliva trapped between the living body and the biologicalinformation detecting probe, though not shown here, be formed in thebottom of the recessed portion of the biological information detectingprobe.

[0215] Further, when light is incident on a portion other than the sidefaces of the recessed portions of the biological information detectingprobe, that is, when light is incident on the top of a raised portion orthe bottom of a recessed portion, much of the light is totallyreflected, and may be emitted from the biological information detectingprobe and reach the detector. Since such light does not containbiological information, it is not preferable to detect such lighttogether with light containing biological information. It is thereforepreferable that light absorbing means, such as the light blocking films312 to 314 described above, be formed on the top of each raised portionor the bottom of each recessed portion.

[0216] Any absorbing means may be used as long as it can absorb light atthe wavelengths used; for example, when the detection light haswavelengths of 9 to 10 microns, use can be made of an oxide film such asa silicon dioxide film or a titanium dioxide film, or a nitride filmsuch as a silicon nitride film. It is preferable that a multilayer filmconsisting of such material and silver or tungsten silicide be formed tofurther enhance the absorbing ability by using the interference effectof light.

[0217] Each of the above embodiments has been described for the casewhere the recessed portions and raised portions are all formed with thesame height, but instead, recessed portions and raised portions withdifferent heights may be formed. In that case, since the superficialtissue of a living body is pressed to various depths, information in thedepth direction can be obtained at a time by detecting informationconcerning the epidermis with a shallow recessed portion and biologicalinformation concerning the dermis with a deep recessed portion at thesame time.

[0218] The shape of the biological information detecting probe in thedepth direction is not specifically limited, but the raised portions 33may be elongated in one particular direction as shown in FIG. 9 By soforming, biological information can be detected by pressing thelongitudinally elongated raised portions 33 into the living tissue andpassing light through each recessed portion. Since longitudinallyelongating the raised portions has the effect of increasing the contactarea with the living body, the area of the beam passing through thesuperficial tissue can be increased; this offers the effect of beingable to improve the S/N of the detection light.

[0219] Further, as shown in FIG. 7, the raised portions 33 may bearranged in a two dimensional array. By so arranging, the raisedportions can be easily pressed into the living tissue, offering theeffect of enhancing the adhesion to the living body and ensuring stablemeasurement.

[0220] As described above, in one example, the biological informationdetecting probe of the present invention is characterized by comprisinga recessed portion which is brought into intimate contact with a livingtissue, and in that the recessed portion is formed so that light emittedfrom one side face of the recessed portion again enters the recessedportion from the other side face thereof after passing through theliving tissue, and in that the biological information detecting probe isformed from a material having a higher refractive index than the livingtissue.

[0221] Preferably, the biological information detecting probe comprisesa plurality of such recessed portions.

[0222] Also preferably, the biological information detecting probecomprises at least two recessed portions having different depths.

[0223] Further preferably, the biological information detecting probe isformed from Si, Ge, SiC, or diamond.

[0224] In one example, the biological information measuring apparatus ofthe present invention is characterized by comprising the above-describedbiological information detecting probe, a light source for detectionlight, and an analyzing means for analyzing the detection light passedthrough a living tissue and introduced into the biological informationdetecting probe, and in that the biological information measuringapparatus acquires biological information based on an analysis resultobtained from the analyzing means.

[0225] Alternatively, the biological information measuring apparatus ofthe present invention may comprise the above-described biologicalinformation detecting probe, a light source for detection light, and ananalyzing means for analyzing scattered light generated when thedetection light is introduced into the living tissue, wherein thebiological information measuring apparatus acquires biologicalinformation based on an analysis result obtained from the analyzingmeans.

[0226] In one example, the biological information measurement method ofthe present invention characterized by comprising a deforming step fordeforming a portion of a living tissue by using the above-describedbiological information detecting probe, a detection light entering andexiting step for causing detection light to enter and exit the livingtissue deformed in the deforming step, and a biological informationanalyzing step for acquiring biological information by analyzing thedetection light passed through the deformed living tissue.

[0227] In an alternative example, the biological information measurementmethod of the present invention comprises a deforming step for deforminga portion of a living tissue by using the above-described biologicalinformation detecting probe, a detection light entering and exiting stepfor causing detection light to enter and exit the living tissue deformedin the deforming step, and a biological information analyzing step foracquiring biological information by analyzing scattered light generatedwhen the detection light is introduced into the deformed living tissue.

[0228] The biological information detecting probe of the presentinvention may, as one example, comprise a recessed portion which isbrought into intimate contact with a living tissue, wherein the recessedportion is formed so that light emitted from one side face of therecessed portion again enters the recessed portion from the other sideface thereof after passing through the living tissue, and wherein thebiological information detecting probe is formed from a material havinga higher refractive index than the living tissue. With thisconfiguration, since the depth at which the detection light passesthrough the living tissue can be controlled by adjusting the depth ofthe recessed portion, biological information concerning the target layerin the living tissue can be measured easily and with high sensitivity byusing the above biological information detecting probe. Furthermore,since much of the detection light introduced into the living tissue canbe fed back to the biological information detecting probe, damage to theliving tissue can be reduced, and the problem of burning caused by theprojection of the detection light can be eliminated.

[0229] It is preferable that there are a plurality of such recessedportions. In this case, the living tissue can be easily raised when theprobe is placed in intimate contact with the living tissue.

[0230] It is also preferable that there are at least two recessedportions having different depths. Using this biological informationdetecting probe, biological information at various depths of the livingtissue can be obtained simultaneously.

[0231] Any suitable material can be used for the biological informationdetecting probe as long as it has a higher refractive index than theliving tissue to be measured; examples of such material include Si, Ge,SiC, diamond, SiO₂, ZnSe, ZnS, andKrS. Among them, Si, Ge, SiC, ordiamond is preferred because of their high refractive index, hightransmittance at the infrared wavelength band, and excellent mechanicalstrength.

[0232] It is also preferable to coat the biological informationdetecting probe with a thin film of amorphous diamond or the like byplasma CVD or other suitable method, because reflection loss at theinterface of the biological information detecting probe can then bereduced.

[0233] The biological information measuring apparatus, as one example,is characterized by comprising the above-described biologicalinformation detecting probe, a light source for detection light, and ananalyzing means for analyzing the detection light passed through aliving tissue and introduced into the biological information detectingprobe, and in that the biological information measuring apparatusacquires biological information based on an analysis result obtainedfrom the analyzing means.

[0234] Here, any suitable light source that emits light at theabsorption wavelength of the substance to be measured can be used forthe light source; examples include a globar light source sintered ofcarbonized silicon SiC in stick shape, a CO₂ laser light source, atungsten lamp, etc. For the measurement of glucose, the globar lightsource is preferred because it can cover a relatively wide wavelengthrange and can produce excellent light even at longer wavelengths ofabout 10 microns.

[0235] For the analyzing means, any suitable method can be used as longas it can measure various state changes caused by molecular vibrationsthat occur when the substance to be measured absorbs light; for example,a Fourier transform infrared spectroscopic analysis method or anopto-acoustic measurement method can be used.

[0236] The biological information measuring apparatus of the presentinvention, as an alternative example, is characterized by comprising theabove-described biological information detecting probe, a light sourcefor detection light, and an analyzing means for analyzing scatteredlight generated when the detection light is introduced into the livingtissue, and in that the biological information measuring apparatusacquires biological information based on an analysis result obtainedfrom the analyzing means.

[0237] Here, for the light source, any suitable light source can be usedas long as it can emit light that undergoes scattering when it isintroduced into the living tissue; examples include an argon laser, aYAG laser, and a semiconductor laser.

[0238] For the analyzing means, any suitable method can be used as longas it can measure various state changes caused by molecular vibrationsthat occur when the substance to be measured absorbs light; for example,Fourier transform Raman spectroscopy may be used.

[0239] The biological information measurement method of the presentinvention, as one example, is characterized by comprising a deformingstep for deforming a portion of a living tissue by using theabove-described biological information detecting probe, a detectionlight entering and exiting step for causing detection light to enter andexit the living tissue deformed in the deforming step, and a biologicalinformation analyzing step for acquiring biological information byanalyzing the detection light passed through the deformed living tissue.

[0240] The biological information measurement method of the presentinvention, as an alternative example, is characterized by comprising adeforming step for deforming a portion of a living tissue by using theabove-described biological information detecting probe, a detectionlight entering and exiting step for causing detection light to enter andexit the living tissue deformed in the deforming step, and a biologicalinformation analyzing step for acquiring biological information byanalyzing scattered light generated when the detection light isintroduced into the deformed living tissue.

[0241] Potential for Exploitation in Industry

[0242] As is apparent from the above description, the present inventioncan provide a biological information detecting probe and a biologicalinformation measuring apparatus that can press a light sensor against asurface of a living body in extremely good contacting relationship andcan easily measure information concerning deep portions of the livingbody, and a biological information measurement method for implementingthe same.

[0243] The present invention can also provide a biological informationdetecting probe and a biological information measuring apparatus thatare easy to handle and can easily carry out highly accurate measurementswhile minimizing damage to a living tissue, and a biological informationmeasurement method for implementing the same.

What is claimed is:
 1. (Amended) A biological information detectingprobe characterized by comprising: pressing means having a recessedportion which is pressed against a living tissue; detection lightemitting means of emitting detection light through one part of saidrecessed portion; and detection light entrance means which is providedin another part of said recessed portion, and into which said detectionlight is introduced, and in that: said pressing means is formed from amaterial that has a higher refractive index than said living tissue; andwith said pressing means held pressed against said living tissue, saiddetection light is introduced into said detection light entrance meansafter being passed through said living tissue fitted into said recessedportion.
 2. The biological information detecting probe as set forth inclaim 1, characterized in that the angle formed by a plane containingsaid one part of said recessed portion through which said detectionlight is emitted makes, and a plane containing said other part of saidrecessed portion through which said detection light enters is smallerthan 180°.
 3. The biological information detecting probe as set forth inclaim 1 or 2, characterized by comprising: a living tissue pressing partwhich is pressed against said living tissue and thereby deforms aportion of said living tissue; and a base part which contacts a portionof said living tissue other than the portion thereof against which saidliving tissue pressing part is pressed, and in that: said pressing meansis formed extending over said living tissue pressing part and said basepart.
 4. The biological information detecting probe as set forth inclaim 3, characterized in that said living tissue pressing part and/orsaid base part include secretion removing means of removing secretionreleased from said living tissue, said secretion removing means beinglocated in a portion contacting said living tissue.
 5. The biologicalinformation detecting probe as set forth in claim 3 or 4, characterizedin that said detection light emitting means is provided in said livingtissue pressing part, and said detection light entrance means isprovided in said base part.
 6. The biological information detectingprobe as set forth in claim 3 or 4, characterized in that said detectionlight emitting means is provided in said base part, and said detectionlight entrance means is provided in said living tissue pressing part. 7.The biological information detecting probe as set forth in claim 5 or 6,characterized in that said detection light emitting means and/or saiddetection light entrance means include an optical waveguide. 8.(Amended) The biological information detecting probe as set forth inclaim 7, characterized in that said optical waveguide has a Y-branchshape or a plate-like shape.
 9. The biological information detectingprobe as set forth in claim 7 or 8, characterized in that said opticalwaveguide in said detection light emitting means is for receivingexternal input light, and an end face of said optical waveguide, fromwhich said detection light is not emitted, is formed so as to guide saidinput light to an end face from which said detection light is emitted.10. The biological information detecting probe as set forth in claim 9,characterized in that said end face of said optical waveguide from whichsaid detection light is not emitted totally reflects said input lightfor input into said optical waveguide.
 11. The biological informationdetecting probe as set forth in claim 9, characterized in that all orpart of said end face of said optical waveguide from which saiddetection light is not emitted has a grating structure, and said gratingstructure diffracts said input light for input into said opticalwaveguide.
 12. (Amended) The biological information detecting probe asset forth in claim 7, characterized in that said optical waveguide isformed from a material selected from the group consisting at least ofgermanium, silicon, and diamond.
 13. (Amended) The biologicalinformation detecting probe as set forth in claim 7, characterized inthat said optical waveguide is surrounded with a cladding material. 14.The biological information detecting probe as set forth in claim 13,characterized in that said optical waveguide is surrounded with acladding material that has a lower refractive index than said opticalwaveguide.
 15. The biological information detecting probe as set forthin claim 1, characterized in that said base part is formed from asilicon material.
 16. A fabrication method for the biologicalinformation detecting probe as set forth in any one of claims 1 to 15,including the step of forming said detection light emitting means and/orsaid detection light entrance means by depositing a germanium material.17. (Deleted)
 18. The biological information detecting probe as setforth in claim 1, characterized in that said recessed portion isprovided with a first light blocking film for blocking said detectionlight, said first light blocking film being formed on a part of saidrecessed portion other than said one part and said other part thereof.19. The biological information detecting probe as set forth in claim 1or 18, characterized in that said recessed portion is substantially inthe shape of an inverted triangle in a cross section taken parallel to alight path of said detection light, and a bottom of said recessedportion does not form a face.
 20. The biological information detectingprobe as set forth in claim 1 or 18, characterized in that said recessedportion is formed so as to have a face at its bottom.
 21. The biologicalinformation detecting probe as set forth in claim 20, characterized inthat the part on which said first light blocking film is formed is thebottom of said recessed portion.
 22. The biological informationdetecting probe as set forth in claim 1 or 18, characterized in that aplurality of said recessed portions are provided.
 23. The biologicalinformation detecting probe as set forth in claim 22, characterized bycomprising a second light blocking film formed between said plurality ofrecessed portions.
 24. The biological information detecting probe as setforth in claim 22, characterized in that the light path of saiddetection light is one that is projected from said detection lightemitting means at an angle smaller than the angle formed by a straightline joining the bottom of said recessed portion to an edge of anotherrecessed portion adjacent to said recessed portion, said edge being thepart thereof nearest to said bottom, and a straight line passing throughsaid edges of said plurality of recessed portions.
 25. The biologicalinformation detecting probe as set forth in claim 22, characterized inthat said plurality of recessed portions comprise at least two recessedportions having different depths.
 26. (Amended) The biologicalinformation detecting probe as set forth in any one of claims 16 or 18to 25, characterized in that said pressing means is formed from Si, Ge,SiC, or diamond.
 27. (Amended) A biological information measuringapparatus characterized by comprising: the biological informationdetecting probe as set forth in any one of claims 1 to 15 or 18 to 25; alight source for said detection light; and analyzing means of analyzingsaid detection light passed through said living tissue and introducedinto said biological information detecting probe, and in that: saidbiological information measuring apparatus acquires biologicalinformation based on an analysis result obtained from said analyzingmeans.
 28. (Amended) A biological information measuring apparatuscharacterized by comprising: the biological information detecting probeas set forth in any one of claims 1 to 15 or 18 to 25; a light sourcefor said detection light; and analyzing means of analyzing scatteredlight generated when said detection light is introduced into said livingtissue, and in that: said biological information measuring apparatusacquires biological information based on an analysis result obtainedfrom said analyzing means.
 29. (Deleted)
 30. (Deleted)
 31. (Amended) Thebiological information measuring apparatus as set forth in claim 27 or28, characterized in that said biological information detecting probedepresses said living tissue to a depth not greater than 5 mm. 32.(Amended) The biological information measuring apparatus as set forth inclaim 27 or 28, characterized in that said biological informationdetecting probe depresses said living tissue into a substantially curvedshape.
 33. (Amended) The biological information measuring apparatus asset forth in claim 27 or 28, characterized in that the angle formed by acontact face that contacts and depresses said living tissue, and a lineperpendicular to a plane containing said living tissue other than saidcontact face is not smaller than 90°.